Leaf Smut

Leaf smut, caused by the fungus Entyloma oryzae, is a widely distributed, but somewhat minor, disease of rice. The fungus produces slightly raised, angular, black spots (sori) on both sides of the leaves.  Although rare, it also can produce spots on leaf sheaths.  The black spots are about 0.5 to 5.0 millimeters long and 0.5 to 1.5 millimeters wide.  Many spots can be found on the same leaf, but the spots remain distinct from each other.  The epidermis breaks open when wet and releases the black spores.  Heavily infected leaves turn yellow, and the leaf tips die and turn gray.